ATM and cancer: Analysis of spontaneous and irradiation-induced chromosomal aberrations in lymphocytes of healthy donors, cancer patients, individuals with ATM serine/threonine kinase (ATM) and Nibrin (NBS1) mutations, and radiosensitive patients [54] confirmed that ATM and NBS1 homozygous patients had the highest incidence of aberrations; while among the radiosensitive group, outliers with high chromosomal breakage were detected.